A continuing study of surgically induced varicocele in monkeys is being correlated with clinic findings in patients with varicocele. Common findings include elevated left hemiscrotal temperatures and enlarged left pampiniform plexus vessels. The monkeys have had transient decreases in sperm concentration, motility, and percent normal morphology following the initial surgery, a partial restriction of the left renal vein. Intratesticular temperature in the varicocele monkeys are elevated in the left testes. Animals in a preliminary study have had ultrastructural changes in the testicular histology affecting the vessels of the interstitial space, basal lamina, and various stages of spermatogenesis. The preliminary studies suggest that reflux of adrenal metabolites is not a causal factor of decreased semen parameters in varicocele subjects. The current study is also investigating biochemical changes in semen collected from both animal and human subjects. The correlation of these data will provide important information concerning the progressive nature of varicocele in men.